How Fuel Gauges Work

If you're like me, you like to squeeze every last mile you can out of your tank of fuel. If you could get 20 miles extra from each tank, that could save you two or three trips to the gas station over the course of a year.

The main impediment to stretching your mileage is the fuel gauge on your car, which makes you think you have less fuel than you actually do. These devices are notoriously inaccurate, showing empty when there are gallons left in the tank and showing full for the first 50 miles.

In this article, we'll learn why our fuel gauges behave the way they do. There are two main parts to a fuel gauge: the sender, which measures the level of fuel in the tank, and the gauge, which displays that level to the driver. First, let's see how a typical sender works.